Domain intercommunication in shared computing environments

ABSTRACT

A method, system, and computer program product for enabling communication between different overlay solutions. The method includes one or more processor obtaining an address resolution request from a first resource in a first domain for a second resource in a second domain. Both domains are in a shared computing environment and the second domain includes a control plane engine. The one or more processor obtains source information from the request, registers the information to the engine, and utilizes the request to query the engine to locate the second resource in the domain. The second resource matches the request. The processor receives a response from the engine identifying a first host and the first host is in the second domain and is the host of the second resource. The processor sends a notification request to the first host requesting that the first host reply to the request.

TECHNICAL FIELD

One or more aspects of the present invention relates to enablingcommunication between different overlay solutions in a shared computingenvironment.

BACKGROUND

In order to deploy seemingly dedicated resources to users of a sharedcomputing environment, including but not limited to a cloud computingsystem, different solutions are introduced that create overlay networkson top of existing networks, by generating logical communication linksbetween hosts within a service domain. One approach to implementing anoverlay network includes tunneling, where a delivery network protocolencapsulates a payload protocol. However, various implementations ofoverlay network solutions are not always compatible with each other orable to communicate with each other. Two such approaches are VirtualExtensible Local Area Network (VXLAN) and Centralized NVO3Implementation (CNI), as they differ in their implementations about theControl Planes (CPs), though they have the same frame encapsulation.Devices in one area of a computing environment utilizing VXLAN cannotcommunicate with devices in another area of a computing environmentusing CNI and vice versa because tunnel information from one solutioncannot be introduced in the other.

VXLAN and CNI communicate in different ways in the CP. VXLAN has nodedicated CP and uses multicast tunnels for address resolution. CNI usesa centralized policy server, including a centralized controller and acentralized policy manager, to support tunnel resolution instead of therelying on a multicast query scheme, which is the core tunnel resolutionmechanism of VXLAN. In CNI, tunnel endpoints are registered on thecontroller. Thus, a VM hosted in a VXLAN domain cannot communicate witha VM hosted in a CNI domain directly over an overlay network because ofdifferent address resolve mechanisms in the CP, even if both VMs use aVXLAN frame for tunneling.

SUMMARY

Shortcomings of the prior art are overcome and additional advantages areprovided through the provision of a method of enabling communicationbetween two domains in a shared computing environment. The methodincludes, for instance: obtaining, by the one or more processor, anaddress resolution request from a first resource in a first domain for asecond resource in a second domain, wherein a shared computingenvironment comprises the first domain and the second domain, andwherein the second domain comprises a control plane engine; obtaining,by the one or more processor, source information from the addressresolution request; registering, by the one or more processor, thesource information to the control plane engine, and utilizing theaddress resolution request to query the control plane engine to locatethe second resource in the domain, wherein the second resource matchesthe address resolution request; receiving, by the one or more processor,a response from the control plane engine identifying a first host,wherein the first host is in the second domain and is the host of thesecond resource; and sending, by the one or more processor, anotification request to the first host requesting that the first hostreply to the address resolution request.

Shortcomings of the prior art are overcome and additional advantages areprovided through the provision of a computer program product to ofenable communication between two domains in a shared computingenvironment. The computer program product includes, for instance, acomputer readable storage medium readable by a processing circuit andstoring instructions for execution by the processing circuit forperforming a method including: obtaining, by the one or more processor,an address resolution request from a first resource in a first domainfor a second resource in a second domain, wherein a shared computingenvironment comprises the first domain and the second domain, andwherein the second domain comprises a control plane engine; obtaining,by the one or more processor, source information from the addressresolution request; registering, by the one or more processor, thesource information to the control plane engine, and utilizing theaddress resolution request to query the control plane engine to locatethe second resource in the domain, wherein the second resource matchesthe address resolution request; receiving, by the one or more processor,a response from the control plane engine identifying a first host,wherein the first host is in the second domain and is the host of thesecond resource; and sending, by the one or more processor, anotification request to the first host requesting that the first hostreply to the address resolution request.

Computer systems and methods relating to one or more aspects of thetechnique are also described and may be claimed herein. Further,services relating to one or more aspects of the technique are alsodescribed and may be claimed herein.

Additional features and are realized through the techniques of thepresent invention. Other embodiments and aspects of the invention aredescribed in detail herein and are considered a part of the claimedinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more aspects of the present invention are particularly pointedout and distinctly claimed as examples in the claims at the conclusionof the specification. The foregoing and objects, features, andadvantages of one or more aspects of the invention are apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 depicts a cloud computing node, in accordance with one or moreembodiments set forth herein;

FIG. 2 depicts a cloud computing environment, in accordance with one ormore embodiments set forth herein;

FIG. 3 depicts abstraction model layers, in accordance with one or moreembodiments set forth herein;

FIG. 4 depicts a hardware overview of a computing node, in accordancewith one or more embodiments set forth herein;

FIG. 5 depicts an example topography of a shared computing environmentwhere aspects of certain embodiments of the present invention may beimplemented;

FIG. 6 depicts a workflow of an embodiment of the present invention;

FIG. 7 depicts certain aspects of an embodiment of the present inventionutilizing the architecture depicted in FIG. 5;

FIG. 8 depicts a workflow of certain aspects of an embodiment of thepresent invention; and

FIG. 9 depicts certain aspects of an embodiment of the present inventionutilizing the architecture depicted in FIG. 5.

DETAILED DESCRIPTION

The accompanying figures, in which like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which are incorporated in and form a part of the specification,further illustrate the present invention and, together with the detaileddescription of the invention, serve to explain the principles of thepresent invention.

An embodiment of the present invention enables computing resources uponwhich the desperate solutions described above have been implemented tocommunicate directly. As described above, in a shared computingenvironment, including but not limited to a cloud computing system, whena VM hosted in a VXLAN domain cannot communicate directly with a VMhosted in CNI domain by overlay network, or vice versa, because VXLANand CNI utilize different address resolve mechanisms in the CP. VXLANand CNI domains cannot communicate directly in this manner despite thefact that both may use a VXLAN frame for tunneling. Although VXLAN andCNI are used as examples throughout this paper, one of skill in the artwill recognize that aspects of certain embodiments of the presentinvention may be adapted to enable communication over an overlay networkof resources that due to certain technical limitations, cannotcommunicate directly.

VXLAN and CNI were selected as examples because they communicate indifferent ways in the CP.

VXLAN has no dedicated CP, thus, there is no out-of-band mechanism thatcould be used for a VM to discover another host in its segment,including a host's Media Access Control (MAC) address and VXLAN TunnelEndpoint (VTEP) IP addresses, or any other relevant connectivityinformation. Instead, VXLAN uses existing layer 2 mechanisms such asflooding and dynamic MAC learning. Layer 2 broadcast is replaced by IPmulticast, by mapping a VXLAN segment to an IP multicast address,limiting the layer 2 broadcast transmissions to servers hosting VMs inthe same VXLAN segment. VTEPs can join or leave multicast groups asneeded, using The Internet Group Management Protocol (IGMP) (IGMP).Then, Address Resolution Protocol (ARP) is implemented over IP multicastto resolve MAC-to-VTEP mappings.

Unlike in VXLAN, in CNI, data traffic is handled by distributed dataplane entities, each called a Network Virtualization Edge (NVE) whilecontrol is achieved through a CP engine called Network VirtualizationAuthority (NVA). The NVE entities are in charge of connectivity andpolicy enforcement in a CNI environment, and get the respective controlinformation from NVA (if not available in local cache). Typically, a NVEis located on a physical server, and serves the VMs hosted by thisserver. Traffic sent and received by a VM traverses its hosting NVE andthe NVA maintains the logical view of the network. When an NVA detectsthe need to resolve an endpoint address in the CNI domain and it is notaware of the NVE that hosts that endpoint, the NVA sends an addressresolution request to all the NVA Clients on NVE that are known to hostEndpoints from a specific domain. The NVE that finds the requestedEndpoint sends a reply, and the NVA updates its database.

An embodiment of the present invention includes a method forcommunicating information between two control planes in a sharedcomputing environment where resources utilizing the networkvirtualization technologies employed cannot communicate with each otherdirectly utilizing an overlay network because each networkvirtualization technology communicates in a different way in itsrespective CP. An embodiment of the present invention may also include amethod that enables a resource utilizing the first of these networkvirtualization technologies to make a request directly to a resourceutilizing the second of these network virtualization technologies andreceive a direct reply.

Certain embodiments of the present invention may offer various technicalcomputing advantages, including increasing the computing efficiency ofshared computing environments and enabling users to make better use ofresources available in such an environment. For example, certainembodiments of the present invention utilize the existing infrastructureof a shared computing environment, thus, no additional investment inresources is required to implement these embodiments of the presentinvention. Certain embodiments of the present invention offer a user aflexible solution to upgrade existing networks by enabling elements of anetwork to communicate directly that were formerly unable to communicatedirectly. Certain embodiments of the present invention enable a user tomerge different existing overlay networks. Implementing certainembodiments of the present invention can enhance the performance of ashared computing environment as the direct communication betweenresources using different network virtualization technologies ispossible, increasing the efficiency of a system as a whole.Specifically, use of certain embodiments of the present inventioneliminates the 4K VLAN limitation which is a typical limitation of aVXLAN. Aspects of certain embodiments of the present invention enable IPunicast communication between VXLAN domains and CNI domains to becompatible without requiring major changes to the existing structure ofthe shared computing environment where these two solutions wereimplemented. Another advantage of certain embodiments is that comparedwith the traditional gateway meanings, in these select embodiments,there are no centralized facilities to transfer between the two types ofoverlay networks. Rather, VXLAN header encapsulation/de-capsulation ishandled by each NVE in the corresponding domain, so there is not aperformance bottleneck or single point of failure.

As discussed above, certain embodiments of the present invention enablevirtual resources deployed in a middleware layer in a cloud computingenvironment to communicate with each other directly despite theresources utilizing traditionally incompatible network virtualizationtechnologies. Thus, certain embodiments of the present invention areparticularly relevant to increasing the efficiency and communicationswithin a cloud computing environment.

FIGS. 1-4 depict various aspects of computing, including cloudcomputing, in accordance with one or more embodiments set forth herein.

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 1, a schematic of an example of a cloud computingnode is shown. Cloud computing node 10 is only one example of a suitablecloud computing node and is not intended to suggest any limitation as tothe scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, cloud computing node 10 is capable ofbeing implemented and/or performing any of the functionality set forthhereinabove.

In cloud computing node 10 there is a computer system 12, which isoperational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system 12 include, but are not limitedto, personal computer systems, server computer systems, thin clients,thick clients, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputer systems, mainframe computersystems, mobile devices, personal data assistants, and distributed cloudcomputing environments that include any of the above systems or devices,and the like.

Computer system 12 may be described in the general context of computersystem-executable instructions, such as program modules, being executedby a computer system. Generally, program modules may include routines,programs, objects, components, logic, data structures, and so on thatperform particular tasks or implement particular abstract data types.Computer system 12 may be practiced in distributed cloud computingenvironments where tasks are performed by remote processing devices thatare linked through a communications network. In a distributed cloudcomputing environment, program modules may be located in both local andremote computer system storage media including memory storage devices.

As shown in FIG. 1, computer system 12 in cloud computing node 10 isshown in the form of a general-purpose computing device. The componentsof computer system 12 may include, but are not limited to, one or moreprocessors or processing units 16, a system memory 28, and a bus 18 thatcouples various system components including system memory 28 toprocessor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnects (PCI) bus.

Computer system 12 typically includes a variety of computer systemreadable media. Such media may be any available media that is accessibleby computer system/server 12, and it includes both volatile andnon-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computer system12; and/or any devices (e.g., network card, modem, etc.) that enablecomputer system 12 to communicate with one or more other computingdevices. Such communication can occur via Input/Output (I/O) interfaces22. Still yet, computer system 12 can communicate with one or morenetworks such as a local area network (LAN), a general wide area network(WAN), and/or a public network (e.g., the Internet) via network adapter20. As depicted, network adapter 20 communicates with the othercomponents of computer system 12 via bus 18. It should be understoodthat although not shown, other hardware and/or software components couldbe used in conjunction with computer system 12. Examples, include, butare not limited to: microcode, device drivers, redundant processingunits, external disk drive arrays, RAID systems, tape drives, and dataarchival storage systems, etc.

Referring now to FIG. 2, an illustrative cloud computing environment isdepicted, in accordance with one or more embodiments set forth herein.As shown, cloud computing environment 50 comprises one or more cloudcomputing nodes 10 with which local computing devices used by cloudconsumers, such as, for example, personal digital assistant (PDA) orcellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 2 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 3, a set of functional abstraction layers providedby cloud computing environment 50 (FIG. 2) is shown, in accordance withone or more embodiments set forth herein. It should be understood inadvance that the components, layers, and functions shown in FIG. 3 areintended to be illustrative only and embodiments of the invention arenot limited thereto. As depicted, the following layers and correspondingfunctions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and enabling communication between differentoverlay solutions 96, as described herein.

FIG. 4 depicts a hardware overview of a computing node 10, in accordancewith one or more embodiments set forth herein.

Program/utility 40 as set forth in FIG. 1 can include one or moreprogram 440 as set forth in FIG. 4, and can provide the functionality ofenabling communication between different overlay solutions 96 as setforth in FIG. 3.

One or more program 440 can have a set (at least one) of programmodules, and may be stored in memory 28 by way of example, and notlimitation, as well as an operating system, one or more applicationprograms, other program modules, and program data. Each of the operatingsystem, one or more application programs, other program modules, programdata, and one or more program, or some combination thereof, may includean implementation of a networking environment. One or more program 440generally carry out the functions and/or methodologies of embodiments ofthe invention as described herein.

Referring again to FIG. 4:

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

As aforementioned, aspects of various embodiments of the presentinvention include a method for enabling communication between differentoverlay solutions in a shared computing environment. Throughout thisspecification, one or more cloud computing environments 50 (FIG. 2) maybe referenced or pictures may be provided to represent one type ofcomputing environment into which aspects of the present invention may bedeployed. However, the cloud computing environment 50 (FIG. 2) is merelyone example of an environment is which advantages of certain aspects ofsome embodiments of the present invention may be realized.

In an embodiment of the present invention, in order to resolvecommunication between a VXLAN domain and a CNI domain, two elements areimplemented in a shared computing environment. A first element, whichcan be referred to as an Overlay Ferry Proxy (OFP), ferries controlplane information. A second element, which may be referred to as a VXLANRelay Agent (VRA), enables resources in a CNI domain to communicate withresources in a VXLAN domain by enabling the CNI resources to communicatewith the VXLAN resources driven by the OFP.

FIG. 5 depicts an example topography of a shared computing environmentwhere aspects of certain embodiments of the present invention may beimplemented. This shared computing environment includes resourcesutilizing a VXLAN and CNI overlay solutions. The resources use theserespective overlay solutions are depicted as a VXLAN domain 510 and aCNI domain 520. This technical environment will be used to illustratecertain aspects of certain embodiments of the present invention.Specifically, FIG. 5 will illustrate how one or more program 440 (FIG.4), which may be included in an OFP and/or one or more VRA, can enableresources from two incompatible domains within a shared computingenvironment to communicate with each other directly.

Referring to FIG. 5, certain aspects of an embodiment of the presentinvention are implemented in the shared computing environment 500. Asseen in FIG. 5, VXLAN domain 510, which can be understood as a firstdomain, includes VXLAN switches 512 a-512 b and VMs 514 a-514 b. The CNIdomain 520, which can be understood as a second domain, includes NVEs522 a-522 b, VMs 524 a-524 b, a controller 526, and an NVA 528. Both theVXLAN domain 510 and the CNI domain 520 overlay an Underlay IP Network540, which comprises the real (not virtual) resources of the sharedcomputing environment 500. An embodiment of the OFP 530 of the presentinvention is also depicted in FIG. 5 as ferrying communications betweenCPs utilizing a VXLAN Module 542 and a CNI Module 544 to communicatebetween the respective solutions. In an embodiment of the presentinvention, each NVE 522 a-522 b includes a VRA 529 a-529 b such that oneor more program 440 can reply to ARP requests from the VXLAN domain 510(e.g., the VXLAN domain) in the VXLAN way directly by communicating withthe OFP 530.

The OFP 530 includes one or more program 440 (FIG. 4) to communicateinformation between CPs in a shared computing environment. In anembodiment of the present invention, one or more program 440 joins acorresponding multicast group to receive ARP requests from a domainwhere the VXLAN domain 510 is implemented. In an embodiment of thepresent invention, the one or more program 440 will register virtualnetworks in the NVA 528. In an embodiment of the present invention, theone or more program 440 will register each virtual network by thevirtual network ID (VNID) of each network. The one or more program 440forms a proxy between the overlay networks of the VXLAN domain 510 andthe CNI domain 520. As a proxy, the one or more program 440 receives anARP from the VXLAN domain 510, decapsulates the header and registers therequest in the NVA 528 of the CNI domain 520. Conversely, the one ormore program 440 receives a lookup from the NVA 528 for an endpoint(e.g., VM), in a certain VNID and the one or more program 440 convertsthe lookup to a VXLAN query (i.e., an IP multicast for the VNID) intothe VXLAN domain 510.

The NVEs 522 a-522 b that include VRA 529 a-529 b in the CNI domain 520include one or more program 440 (FIG. 4) as well, In an embodiment ofthe present invention, the one or more program 440 obtains ARP requestsfrom the VXLAN domain 510 and replies to these requests via the OFP 530.

FIG. 6 depicts a workflow of an embodiment of the present invention,specifically, an example of how a resource in a first domain resolves aresource in the second domain in accordance with some aspects of thisembodiment of the invention. In an embodiment of the present inventionwhere the first domain is a VXLAN domain and the second domain is a CNIdomain, FIG. 6 is an example of how a resource, including by not limitedto a VM in a VXLAN domain, resolves an endpoint, including but notlimited to a VM, in a CNI domain. The first domain and the second domainboth overlay the same shared computing environment, which may include,but is not limited to, a cloud computing environment.

For ease of understanding, the elements in FIG. 5 are referred tothroughout the description of workflow 600. However, the use of thisexample is only meant as one possible illustration and is not meant asan exclusive topography. The communication between the VXLAN domain 510and the CNI domain 520 is handled by a proxy, which, in an embodiment ofthe present invention, includes OFP 530. Specifically, FIG. 6 depicts anelement in VXLAN domain 510 initiating a communication with an elementof CNI domain 520, and the element of the VXLAN domain 510 receiving aresponse. As aforementioned, the purpose of the communication can be forelements in the VXLAN domain 510 (e.g., VMs) to resolve endpoints in theCNI domain 520 (e.g., VMs). In an embodiment of the present invention,one or more program 440 (FIG. 440) executing on a resource in the VXLANdomain 510, for example, the resource may be a VM 514 a-514 b and theone or more program 440 may obtain the request from this resource via aVXLAN switch 512 b. The first resource may request the destinationendpoint tunnel IP for a host in the CNI domain 520. As explained inmore detail below, in an embodiment of the present invention, an elementin the CNI domain 520, for example, destination NVE 522 a, carrying thedestination VM 524 a, may respond to the request.

Returning to FIG. 6, in accordance with an embodiment of the presentinvention, one or more program 440 (FIG. 4) obtains an addressresolution request from a first resource in a first domain for a secondresource in a second domain (615). In an embodiment of the presentinvention, the one or more program 440 obtains the address resolutionrequest utilizing an Address Resolution Protocol (ARP). In this example,the one or more program 440 obtains an ARP request to find a destinationVM MAC address. In an embodiment of the present invention, the firstdomain does not have a dedicated CP and/or the second domain has a CPengine that is communicatively coupled to a centralized controller uponwhich the resource is registered. In an embodiment of the presentinvention, the first domain is VXLAN domain 510. In a further embodimentof the present invention, the second domain is CNI domain 520. In afurther embodiment of the present invention, the one or more program 440obtains the address resolution request from a switch in the firstdomain. In an embodiment of the present invention, the request is anencapsulated packet. The encapsulated packet may have been encapsulatedby a VXLAN switch in the first domain, which encapsulated the addressresolution request (e.g., ARP request) with a VXLAN header. In anembodiment of the present invention, the address resolution request maybe multicast to hosts in a common multicast group and the proxy thatwill enable communication between the two domains, including but notlimited to OFP 530 is an example, is a member of this common multicastgroup.

The one or more program 440 obtains source information from the addressresolution request, registers the source information to a CP engine inthe second domain, and queries the CP engine to locate the secondresource in the second domain, where the second resource matches theaddress resolution request (625). In an embodiment of the presentinvention, the CP engine is an NVA. In an embodiment of the presentinvention, the source information comprises the source VM tunnelresolution information from the first domain. In an embodiment of thepresent invention, if the source information is already registered inthe CP engine, the one or more program 440 will update the existinginformation in the CP engine in accordance with the address resolutionrequest. The query may include checking data in an NVA to see if thereis an endpoint (e.g., a VM) that matches the request.

Based on querying the CP engine, the one or more program 440 receives aresponse from the CP engine identifying a host in the second domain ofthe second resource identified in the address resolution request (635).There are a number of ways that the control plane engine can identifythe second resource. First, the information identifying the host may beaccessible to the one or more program 440 directly in the CP engine.However, responsive to the query, one or more program 440 may send abroadcast to various hosts in the second domain looking for the secondresource in the second domain. In the example where the second domain isa CNI domain, the CP engine may employ a CNI native tunnel resolutionmechanism in making this broadcast.

In an embodiment of the present invention, the one or more program 440sends a notification request to the (identified) host requesting thatthe host reply to the address resolution request (645). In an embodimentof the present invention, the one or more program 440 sends thisnotification request to a VRE located in the host; the host itself maybe a destination NVE. In an embodiment of the present invention, thenotification request includes an instruction to reply to the addressresolution request in a format native to the first domain. For example,if the first domain is a VXLAN domain, the request may include aninstruction to respond with a reply (e.g., an ARP reply), which isencapsulated with a VXLAN encapsulation, which is a format utilized in aVXLAN domain. In an embodiment of the present invention, the host'sreply to the request is a unicast reply. In an embodiment of the presentinvention, a VRA module located in the identified host sends repliesdirectly to the first source. For example, in an embodiment of thepresent invention, the VRA module 529 a-529 b sends an ARP reply withVXLAN encapsulation directly to the source endpoint (i.e., the firstsource) in the VXLAN domain (i.e., the first domain).

In an embodiment of the present invention, in addition to an element inthe first domain communicatively coupled to the first resource receivingthe reply (e.g., an encapsulated VXLAN ARP reply), the element alsoreceives information about the source of this reply. For example, thiselement, which can be, in one example, VXLAN switch 512 a-512 b, mayreceive the destination tunnel IP. In an embodiment of the presentinvention, the element will process the reply, which may include but isnot limited to decapsulating the VXLAN header of the reply, and forwardthis reply, which may be, for example, an ARP reply, to the firstresource, which in an embodiment of the present invention, is VM sourceVM 514 a-514 b. Upon completion of the request and reply sequence, thefirst resource and the second resource have exchanged information andhave data related to other IP-MAC mapping. In an embodiment of thepresent invention, the VXLAN switch and the NVE also have exchangedmappings and thus, these elements can send data to each other viaunicast.

FIG. 7 depicts certain aspects of an embodiment of the present inventionutilizing the architecture depicted in FIG. 5. As aforementioned, thisarchitecture provides one example of a possible topography for a systeminto which aspects of the present invention may be implemented. This ismerely one example of an implementation, as understood by one of skillin the art. Certain connections between architectural elements in FIG. 5were removed in FIG. 7 (as well as in FIG. 9) for illustrative purposes,in order to make the figure easier to follow. Overlaying aspects ofembodiments of the present invention on an example architecture assistsin illustrating aspects of the invention, which is why this technique isemployed herein.

As illustrated in FIG. 7, one or more program 440 creates a proxy, e.g.,OFP 730, to ferry communication between two domains and implements arelay agent on a host in the domain. VRA 729 a-729 b, which are part ofNVE 722 a-722 b, are examples of relay agents. Each domain uses anetwork overlay solution and these domains both overlay a commonUnderlay IP Network 740 in a shared computing environment. One or moreprogram 440 obtains an address resolution request from a first resourcein a first domain, a VXLAN domain 710, for a second resource in a seconddomain, a CNI domain 720 (715). One or more program 440 obtains sourceinformation from the request, registers the source information to a CPengine, e.g., NVA 728, and queries the CP engine to locate the secondresource in the second domain matching the address resolution request(725). The one or more program 440 receives a response from the controlplane engine identifying a host (e.g., NVE 722 a-722 b) in the seconddomain of the second resource identified in the address resolutionrequest (735). The resources in this domain include VMs 724 a-724 b. Oneor more program 440 sends a notification request to the host requestingthat the host reply to the address resolution request in a specifiedformat (745). The VRA module 729 a sends a reply (e.g., an ARP reply),in the specified format (e.g., with VXLAN encapsulation) directly to thefirst resource, the source endpoint, in the first domain, a VXLAN domain710 (755). As seen in FIG. 7, both the request and the reply areprocessed by a switch in the first domain 710 either after or in advanceof being obtained by the first resource, a VM 714 b. As is depicted inFIG. 7, the VXLAN switch 712 b and the NVE 722 a serve as gateways toaccess VM 714 b and VM 724 a, respectively. Similarly, had the exampleutilized different resources in the environment, VXLAN switch 712 a andthe NVE 722 b could also serve as gateways, and these gateways wouldenable access to VM 714 a and VM 724 b.

In an embodiment of the present invention, communications to the OFP 730to and from the VXLAN domain 710 may be received and sent by a VXLANModule 742 in the OFP 730. Communications to and from the CNI domain 720may be received and sent by a CNI Module 744 in the OFP 930. In anembodiment of the present invention, endpoints may be registered on thecontroller 726.

The format and contents of the query the one or more program 440 makesto a CP engine may vary. In an embodiment of the present invention, thisquery may include some of the following information: Target VNID, Packettype: ARP Response, Source NVE (Tunnel Endpoint) IP, Source VM IPaddress, Source VM MAC address, Destination VM IP address, DestinationVM MAC address.

While FIGS. 6-7 depict workflows that include communications from afirst domain, an overlay network utilizing an overlay solution without adedicated CP, to a second domain, an overlay network utilizing anoverlay solution with a domain CP engine, FIGS. 8-9 depict the oppositecommunication, from the second domain to the first domain, in accordancewith certain aspects of an embodiment of the present invention.Specifically, FIG. 8 depicts a resource in the second domain resolvingfor a resource (endpoint) in the first domain. In an embodiment of thepresent invention, at least one of the resources is a VM. In anembodiment of the present invention, the second domain in CNI domain 520and the first domain is VXLAN domain 510. In an embodiment of thepresent invention, the communication between these domains is managedthrough a proxy, for example, the aforementioned OFP 530.

As with FIG. 6, in FIG. 8, elements of the example topography of FIG. 5are utilized in the description of workflow 800. This topography is onlyoffered for ease of understanding and is only an example of onetopography in which aspects of some embodiments of the present inventionmay be implemented.

FIG. 8 illustrates a workflow that commences when one or more program440 obtains an address request from a domain control plane engine.Before one or more program 440 obtains the request, certain events mayoccur within the technical environment in which aspects of the presentinvention are implemented. In an embodiment of the present invention,when a resource in the second domain (e.g., VMs 524 a-524 b), which canbe CNI domain 520, seeks address information for another resource, theresource in the second domain queries the domain CP engine (e.g., NVA528)) to locate the destination endpoint. Without this endpointinformation, the resource in the second domain cannot communicatedirectly with another resource. Thus, in this example, the resource inthe second domain can communicate directly with resources that areregistered in the domain CP engine. Thus, when a resource in the firstdomain queries the domain CP engine for endpoint mapping informationrelated to a resource in the first domain and the domain CP enginecannot find the destination endpoint mapping information, the domain CPengine floods all hosts within the second domain, including but notlimited to, hosts related to a proxy, for example OFP 530, which mayinclude one or more program 440.

Referring first to the workflow 800 of FIG. 8, one or more program 440(FIG. 4) obtains a request for a host address endpoint in a first domainfrom a domain control plane engine in the second domain (815). Therequest may comprise an ARP request from a CP engine in CNI domain 520for a host address in VXLAN domain 510. In an embodiment of the presentinvention, this request can originate as a request from a host ofresources, such as VMs 524 a-524 b within the second domain. The hostcan request information, such as VM-host mapping information related tothe first domain from the domain CP engine of the second domain. Basedon the CP engine not having the information requested, the CP engine canbroadcast the request to all hosts to which it was communicativelycoupled, including to one or more program 440, which may be executed bya resource in a proxy, including but not limited to, OFP 530, which iscommunicatively coupled to the resources of the second domain. In anembodiment of the present invention, the CP engine is NVA 528 in CNIdomain 520.

In an embodiment of the present invention, based on obtaining therequest, the one or more program 440 sends a multicast address query tohosts in the first domain (825). Responsive to this query, one or moreprogram 440 receives a response from a host in the first domain (835).In an embodiment of the present invention, this host is the host ofcertain resources in the domain, including but not limited to VMs. Forexample, in an embodiment of the present invention where the firstdomain is VXLAN domain 510, the host may be VXLAN switch 512 a-512 b andthe resource may be VM 514 a-514 b hosted by the VXLAN switch 512 a-512b.

In response to receiving the response, the one or more program 440 sendsthe response to the CP engine of the second domain to register theresource from the first domain in the CP engine (845). Based on the oneor more program 440 registering the resource in the CP engine, the CPengine replies to the host in the second domain, which originated therequest. The one or more program 440 can register the resource in the CPengine by creating a mapping for the resource in the CP engine. In anembodiment of the present invention, the one or more program 440registers the resource from the first domain in the same way that theresources in the second domain are registered in the CP engine. Thus, inan embodiment of the present invention where the first domain is VXLANdomain 510 and the second domain is CNI domain, the one or more program440 gathers the reply, which may be a response to an AFP request, andregisters the resource, for example, VM 514 a-514 b from the VXLANdomain 510, to the NVA 528 in the CNI domain 520, in the same mannerthat the hosts in the CNI domain 510, such as NVEs 522 a-522 b, registera resource in the CNI domain 510, such as VMs 524 a-524 b. In anembodiment of the present invention, the CP engine responds to thesource endpoint in the second domain with the destination endpointmapping information from the first domain, enabling the source in thesecond domain to send traffic to this destination in the first domain(855).

Registering resources from the first domain in the CP engine of thesecond domain enables intra-domain communications by providing VM-hostmapping info. In an embodiment of the present invention, in response tothe host receiving this reply from the CP engine, the host can sendtraffic to the resource in the first domain. In an embodiment where thesecond domain is CNI domain 520, the CP engine can be NVA 528 and thehost can be NVE 522 a-522 b. For example, with the mapping information,NVE 522 a-522 b can find the tunnel resolution for the requestedresource (e.g., VM 514 a-514 b) in a data structure, such as a table, inthe CP engine (e.g., NVA 528). In an embodiment of the presentinvention, after registration is complete, endpoint (VM) informationmatching the request of the CNI domain 520 is known to the correspondingNVE 522 a-522 b and the requesting VM 524 a-524 b. Thus, the VM 524a-524 b in the CNI domain 520 can send the traffic to the VM 514 a-514 bin VXLAN domain 510. A VM 524 a-524 b can send VXLAN packets to a knownhost in the VXLAN domain 510 directly.

FIG. 9 depicts certain aspects of an embodiment of the present inventionutilizing the architecture depicted in FIG. 5. As aforementioned, thisarchitecture provides one example of a possible topography for a systeminto which aspects of the present invention may be implemented. This ismerely one example of an implementation, as understood by one of skillin the art. Overlaying aspects of embodiments of the present inventionon an example architecture assists in illustrating aspects of theinvention, which is why this technique is employed herein.

As seen in FIG. 9, one or more program 440 (FIG. 4), in this example,executing on a resource in an OFP 930, obtains a request for a hostaddress endpoint, VM 914 b, in a first domain, VXLAN domain 910 from adomain CP engine, NVA 928, in the second domain, CNI domain 920 (915).As explained above, prior to the one or more program 440 obtaining therequest, a source endpoint, VM 924 a in CNI domain 920 queries the CPengine, NVA 928, to locate a destination endpoint. VM 924 b may alsooriginate this request. As explained above, each resource, e.g., VM 924a and/or VM 924 b, is associated with an NVE, e.g., NVE 922 a and/or NVE922 b. In an embodiment of the present invention, each NVA includes aVRA, depicted in the example as VRA 929 a and VRA 929 b, to enablingthese CNI resources to communicate with the VXLAN resources driven bythe OFP 930.

Based on one or more program 440 executing on a resource in the controlplane engine, NVA 928, not locating the destination endpoint, one ormore program 440 in the CP engine, NVA 928, floods all hosts such thatthe one or more program 440 executing on the OFP 930 obtains thisrequest. It is at this point that the one or more program 440 obtainsthe aforementioned request.

Returning to FIG. 9, the one or more program 440 sends a multicastaddress query to hosts in the first domain, VXLAN domain 910 (925). Asillustrated in FIG. 9, VM 914 a and VM 914 b both receive the multicastquery. The one or more program 440 receives a response from a host,VXLAN switch 912 b, which hosts endpoint requested, VM 914 b, in thefirst domain, VXLAN domain 910 (935). After receiving the response, theone or more program 440 sends the response to the CP engine, NVA 928, ofthe second domain, CNI domain 920, to register the resource from thefirst domain, VXLAN 910, in the CP engine, NVA 928 (945). One or moreprogram 440 in the CP engine responds to the source endpoint in thesecond domain, VM 924 a, with the destination endpoint mappinginformation from the first domain, the mapping to VM 914 b, enabling thesource in the second domain, VM 924 a, to send traffic to thisdestination in the first domain (955).

In an embodiment of the present invention, communications to the OFP 930to and from the VXLAN domain 910 may be received and sent by a VXLANModule 942 in the OFP 930. Communications to and from the CNI domain 920may be received and sent by a CNI Module 944 in the OFP 930. In anembodiment of the present invention, endpoints may be registered on thecontroller 926.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprise” (and any form ofcomprise, such as “comprises” and “comprising”), “have” (and any form ofhave, such as “has” and “having”), “include” (and any form of include,such as “includes” and “including”), and “contain” (and any form ofcontain, such as “contains” and “containing”) are open-ended linkingverbs. As a result, a method or device that “comprises,” “has,”“includes,” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises,” “has,” “includes,” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description set forth herein has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of one or more aspects set forth herein and the practicalapplication, and to enable others of ordinary skill in the art tounderstand one or more aspects as described herein for variousembodiments with various modifications as are suited to the particularuse contemplated.

What is claimed is:
 1. A computer-implemented method comprising:obtaining, by one or more processors, a request from a control planeengine for a first host address endpoint in a first domain from thecontrol plane engine, wherein the control plane engine obtained therequest from a second host in a second domain, and, wherein a sharedcomputing environment comprises the first domain and the second domain,and wherein the second domain comprises the control plane engine; basedon obtaining the request for the first host address endpoint, sending,by the one or more processors, a multicast address query to a group ofhosts in the first domain; responsive to the query, receiving, by theone or more processor, a response from a third host to the request forthe first host address endpoint, wherein the third host is in the firstdomain; and sending, by the one or more processors, the response to thecontrol plane engine to register at least one resource hosted by thethird host in the control plane engine.
 2. The computer-implementedmethod of claim 1, wherein based on registering the resource in thecontrol plane engine, the control plane engine replies to the secondhost and the second host sends data directly to the third host.
 3. Thecomputer-implemented method of claim 1, wherein the first domaincomprises a Centralized NVO3 Implementation (CNI) overlay solution andthe second domain comprises a Virtual Extensible Local Area Network(VXLAN) overlay solution.
 4. The computer-implemented method of claim 1,wherein the first domain and the second domain comprise differentoverlay solutions.
 5. The computer-implemented method of claim 1,further comprising: obtaining, by the one or more processor, an addressresolution request from a first resource in the first domain for asecond resource in the second domain; obtaining, by the one or moreprocessor, source information from the address resolution request;registering, by the one or more processor, the source information to thecontrol plane engine, and utilizing the address resolution request toquery the control plane engine to locate the second resource in thedomain, wherein the second resource matches the address resolutionrequest; receiving, by the one or more processor, a response from thecontrol plane engine identifying the first host, wherein the first hostis in the second domain and is the host of the second resource; andsending, by the one or more processor, a notification request to thefirst host requesting that the first host reply to the addressresolution request.
 6. The method of claim 5, wherein the notificationrequest includes an instruction to reply to the address resolutionrequest in pre-defined format.
 7. The method of claim 5, wherein thefirst domain is devoid of a dedicated control plane.
 8. The method ofclaim 5, wherein the source information comprises VM tunnel resolutioninformation from the first resource.
 9. The method of claim 5, whereinthe identifying the first host comprises sending, by the one or moreprocessor a broadcast to hosts in the second domain.
 10. The method ofclaim 9, wherein the address resolution request comprises anencapsulated packet, the encapsulated packet comprising a header andencapsulated by a host in the first domain communicatively coupled tothe first resource.
 11. The method of claim 10, wherein the obtainingthe source information comprises decapsulating the header of the addressresolution request.
 12. The method of claim 6, wherein the format of theaddress resolution request and the pre-defined format are identical. 13.The method of claim 5, further comprising: obtaining, by the one or moreprocessor, the request and based on the obtaining, sending a replydirectly from the second resource to the first resource.
 14. A computerprogram product comprising: a computer readable storage medium readableby one or more processor and storing instructions for execution by theone or more processor for performing a method comprising: obtaining, bythe one or more processors, a request from a control plane engine for afirst host address endpoint in a first domain from the control planeengine, wherein the control plane engine obtained the request from asecond host in a second domain, and, wherein a shared computingenvironment comprises the first domain and the second domain, andwherein the second domain comprises the control plane engine; based onobtaining the request for the first host address endpoint, sending, bythe one or more processors, a multicast address query to a group ofhosts in the first domain; responsive to the query, receiving, by theone or more processor, a response from a third host to the request forthe first host address endpoint, wherein the third host is in the firstdomain; and sending, by the one or more processors, the response to thecontrol plane engine to register at least one resource hosted by thethird host in the control plane engine.
 15. The computer program productof claim 14, wherein based on registering the resource in the controlplane engine, the control plane engine replies to the second host andthe second host sends data directly to the third host.
 16. The computerprogram product of claim 14, wherein the first domain comprises aCentralized NVO3 Implementation (CNI) overlay solution and the seconddomain comprises a Virtual Extensible Local Area Network (VXLAN) overlaysolution.
 17. The computer program product of claim 15, wherein thefirst domain and the second domain comprise different overlay solutions.18. The computer program product of claim 14, the method furthercomprising: obtaining, by the one or more processor, an addressresolution request from a first resource in the first domain for asecond resource in the second domain; obtaining, by the one or moreprocessor, source information from the address resolution request;registering, by the one or more processor, the source information to thecontrol plane engine, and utilizing the address resolution request toquery the control plane engine to locate the second resource in thedomain, wherein the second resource matches the address resolutionrequest; receiving, by the one or more processor, a response from thecontrol plane engine identifying the first host, wherein the first hostis in the second domain and is the host of the second resource; andsending, by the one or more processor, a notification request to thefirst host requesting that the first host reply to the addressresolution request.
 19. A system comprising: a memory; one or moreprocessor in communication with the memory; and program instructionsexecutable by the one or more processor via the memory to perform amethod, the method comprising: obtaining, by the one or more processors,a request from a control plane engine for a first host address endpointin a first domain from the control plane engine, wherein the controlplane engine obtained the request from a second host in a second domain,and, wherein a shared computing environment comprises the first domainand the second domain, and wherein the second domain comprises thecontrol plane engine; based on obtaining the request for the first hostaddress endpoint, sending, by the one or more processors, a multicastaddress query to a group of hosts in the first domain; responsive to thequery, receiving, by the one or more processor, a response from a thirdhost to the request for the first host address endpoint, wherein thethird host is in the first domain; and sending, by the one or moreprocessors, the response to the control plane engine to register atleast one resource hosted by the third host in the control plane engine.20. The system of claim 19, the method further comprising: obtaining, bythe one or more processor, an address resolution request from a firstresource in the first domain for a second resource in the second domain;obtaining, by the one or more processor, source information from theaddress resolution request; registering, by the one or more processor,the source information to the control plane engine, and utilizing theaddress resolution request to query the control plane engine to locatethe second resource in the domain, wherein the second resource matchesthe address resolution request; receiving, by the one or more processor,a response from the control plane engine identifying the first host,wherein the first host is in the second domain and is the host of thesecond resource; and sending, by the one or more processor, anotification request to the first host requesting that the first hostreply to the address resolution request.